Gefitinib is the first small molecule inhibitor that has directed activity towards EGFR and has shown appreciable response rates in phase Ⅱ trials of patients with previously treated advanced NSCLC. In the posterior analysis of Iressa Dose Evaluation in Advanced Lung Cancer (IDEAL) and IRESSA Survival Evaluation in Lung Cancer (ISEL) trials, the response rate with gefitinib ranges from 2.6% to 10% in wild-type EGFR gene NSCLC patients.